Pipette control device



Aug. 1, 1961 DEMOS 2,994,349

PIPETTE CONTROL DEVICE Filed Oct. 29, 1957 2 Sheets-Sheet l SuctionINVENTOR. y 7PTE T DEMOS W M ATTORNEKS g- 1961 P. T. DEMOS PIPETTECONTROL DEVICE 2 Sheets-Sheet 2 Filed 001:. 29, 1957 INVENTOR. By PEERT: DEMOS ATTORNEYJ %United States Patent Ofiice Patented Aug. 1, 1961Filed Oct. 29, 1957, Ser. No. 693,199 2 4 Claims. (Cl. 14121) Thepresent invention relates to control devices for pipettes and similarapparatus.

While numerous automatic or mechanical pipetting de vices have beenevolved for assisting in facilitating the fwithdrawing of measuredquantities of fluids and the like and delivering the same inpredetermined amounts, such as one or more drops at a time, theindustrial and research chemists, biologists and others still relyheavily upon simple pipette tubes to one end of which the opera- ;torapplies his mouth to draw fluid into the tube, and to the same end ofwhich he then applies a finger to release the fluid in the requirednumber of droplets. The speed with which the researcher, for example,must often accomplish numerous pipetting operations, the requirementthat only one hand be occupied with the pipetting, the irreplaceablemeasure of control aflorded by finger-release ,of the fluid within thepipette, have all been factors in ,causing the rejection in many casesof automatic or aux- Eiliary apparatus.

: The use of the mouth-and-finger technique, however, is lsubject togreat dangers when radio-active liquids or gother poisonous substancesare employed. Despite these dangers, a great number of operators persistin using this ancient technique, relying upon their skill to minimizeaccidents.

An object of the present invention, accordingly, is to provide a. newand improved control device for a pipette and the like that shall permitthe operator to retain the mouth operation and finger control, butwithout any of the above-mentioned dangers, and that shall do so withoutrequiring more than the use of a single hand and with substantially thesame operational movements thereof presently employed in ordinarymouth-and-finger-control pipetting. In summary, this end is achieved byproviding a protective chamber having a suction inlet, a pipette inletand an opening into which a finger may be inserted to control thepipette inlet. Preferred details are later described.

A further object is to provide a novel pipette control 'device that mayalso be employed with more elaborate equipment, if desired.

Other and further objects will be explained hereinafter and will be moreparticularly pointed out in the appended claims.

The invention will now be described in connection with the accompanyingdrawing, FIG. 1, of which is a perspective view of the invention in itsmost elementary form;

FIG. 2 is a side elevation of the same;

FIGS. 3 and 7 are fragmentary views, similar to FIG. 1, ofmodifications;

FIG. 4 is a view, similar to FIG. 2, of a further modification;

'FIG. 5 is an end elevation; and

FIG. 6 is a fragmentary side elevation, upon an enlarged scale, of stilladditional modified pipette control devices.

Referring to FIGS. 1 and 2, a conventional calibrated pipette tube isshown at 1 inserted within a beaker of liquid 3 for the purpose ofwithdrawing a predetermined quantity of the liquid for subsequentadding, one or moredrops at a time, to another container. Thebefore-mentioned ancient, widely employed technique involves applyingsuction by the mouth to the upper end 5 of the pipette tube 1 towithdraw approximately a desired quantity of the liquid from the beaker3 into the tube 1, as at 7. The finger 9 is then applied to the upperend 5 to permit, by releasing and re-applying the finger, the liquidlevel 7 to drop to the precise desired quantity of liquid, as measuredon the pipette calibrations 11. The operator would then, by furtherintermittent release and reapplication of the finger 9, add the liquidin the pipette 1 to another container, drop by drop, as for the purposeof producing certain chemical effects. The previously described dangersare evident when it is considered that the pipette tube is of smalldiameter and that a slightly excessive mouth inhalation by the operatorwill result in potentially dangerous liquids entering the mouth.

This is avoided, in accordance with the invention, by the protectivechamber 13, shown for illustrative purposes in the form of a glass orquartz tube closed at the left-hand end 4 and open at the right-hand end2. The upper end 5 of the pipette tube 1 is inserted into a resilientlygasketed pipette inlet 15. The gasket may, for example, be in the formof an annular grummet 17 having upper and lower lips overlapping theopening 15 in the tube, which opening is preferably, thoughnotessentially, disposed along its lower or bottom surface near theclosed end 4 of the chamber 13. A suction inlet 19, preferably, thoughnot essentially, disposed at the top of the container 13, more centrallylocated therealong, is connected to a mouth piece 21 to which theoperators mouth may be applied, just as the operator has heretoforetaken the end 5 of the pipette 1 into his mouth to apply suction. Theopen end 2 of the chamber 13 isof suflicient dimensions, as is thechamber inner dimension, to permit the finger 9 (that heretofore hasbeen applied to the upper end 5 of the pipette 1) to be inserted orreceived therein to a point where a portion of the finger, shown as theforward part, is juxtaposed to the pipette inlet 51517.

By providing a resilient sealing lining 6, as of rubber and the like, atleast in the region of the open end 2 of the chamber 13, the indexfinger 9 may be sealed within the chamber 13. With the finger raised toan upper position of insertion out of contact with the pipette inlet5-15-17, the operator applies suction to the mouth piece 21, drawing theliquid 7 into the pipette 1, under the control of the upper surface ofthe finger 9 cooperatingwith the lower periphery of the inlet 19 in avalving manner. The chamber 13 provides a protective preferablytransparent reservoir that would have to be filled before any liquidcould even enter the mouth piece'zl, thus entirely safe-guarding theoperator. "Upon remov ing the mouth from the mouth piece 21, so as tobreak the suction, air may be allowed to enter the chamber 13 under thecontrol of the valving action of the upper surface of the finger 9cooperating with the lower periphery of the inlet 19, as the operatorlowers the finger 9 to a lowered position of insertion so that its lowerportion covers the pipette inlet 51517 and then, with precisely the samefinger movements to which he has long been accustomed, proceeds with thefurther drop-release operations.

If, moreover, the liquid is not only damaging to the mouth (which dangerhas now been overcome by the present invention), but, also, to the skin,the operator may use a preferably flexible protective finger sleeve 8,FIG. 1,

which may, if desired, be attached to the resilient sealing may beoperated during the application of suction to provide for precisemeasurement of the quantity of liquid withdrawn into the pipette tube. 7

Where external suction apparatus is to be employed, a mechanical valvemeans for releasing the suction and applying atmospheric pressure to thechamber 13 by letting air therein, is preferably employed. Such a valvemeans, in the simple form of a resiliently g'asketed further opening, isshown in FIG. 3 at 10. When the finger 9 is moved to the dotted lowerposition, the valve opening 10 is closed and suction may be applied at2.1 as before. When the finger is moved to the solid-line raisedposition, as in FIGS. 1 and 2, however, the valve is actuated so thatthe opening 10 communicates the chamber suction inlet 19 with theatmosphere and the suction is relieved or released so thatfinger-control may be efiective at the pipette inlet -1517.

The valve opening need not be in the lateral forward position of FIG. 3,moreover, but may be in any position where the finger 9 can convenientlycover the same and also move to cover the pipette inlet. Thus, as afurtherillustration, in FIG. 4, the valve opening 10 is shown to theright of the suction inlet 19 and communicating with the upper portionof the index finger 9.

External valve control may also be effected, if desired. In FIG. 5, forexample, the lateral valve opening 10 communicates with a closed-endedextension 12 having a small opening 14 in the vicinity of the finger 9'next to the index finger 9. The finger 9' may thus control the valveopening 1014 externally to the chamber 13 and without deviating from thenormal position of the pipette operator's hand. To provide a finger restand a greater measure of stability, asupporting rod 16 may be providedsomewhat coextensive with the valve extension 12.

A more complicated mechanical mechanism is illustrated in FIG. 6 whereinupward movement of the index finger 9, shown in solid lines, may operatea plunger valve mechanism 18 in opposition to the biasing action of anattached spring 20, thus to block the air opening 10 but to permitsuction to be applied to the chamber 13. Lowering of the finger to thedotted position will release the plunger 18 downward to its dotted-lineposition, closing ofl? the suction tube 21 by means of the upper portion18' of the plunger, and opening the air inlet 10 to permit the chamber13 to become exposed to atmospheric pressure. Other types of valvingmechanisms, including etlectrically operated solenoid devices mayobviously also be employed.

herein and in the claims. Further modifications will,:'

moreover, occur to those skilled in the art and all such are consideredto fall within the spirit and scope of the invention as defined in theappended claims.

What is claimed is:

1. A finger-operable control device for use with a pipette and the likecomprising a chamber closed at one end and open at the other end toreceive a finger, the chamber being provided with a suction inlet and apippette inlet the latter of which is disposed to be covered by thefinger when in a first position of insertion within the chamber, thesaid chamber suction inlet being communicable with the atmosphere andhaving means for enabling valving of the suction inlet by the actuationof the finger when in a second position of insertion within the chamber,such actuation permitting the introduction of air through the suctioninlet into the chamber in order to break the suction, and means forsealing the said one end of the chamber about the inserted finger.

2. A finger-operable control device as claimed in claim 1 and in whichthe said sealing means comprises a resilient lining disposed within thesaid other end of the said chamber.

3. A finger-operable control device as claimed in claim external to thesaid suction inlet to the said chamber.

References Cited in the file of this patent UNITED STATES PATENTS553,044 Sharples Jan. 14, 1869 1 1,092,384 Nickels Apr. 7, 19141,791,829 McCrackan Feb. 10, 1931

